Babcock-hitachi Kabushiki Kaisha

Shigeru Nozawa

Masakatsu Nishimura

Takanori Nakamoto

Fumito Nakajima

Hirofumi Kikkawa

Shigehito Takamoto

Hiroshi Ishizaka

Hiroyuki Kaku

Hiroshi Kuroda

Tsukasa Nishimura

Osamu Kanda

Taiki Hashimoto

Shigeyoshi Kawano

Toshio Katsube

Atsushi Katagawa

Kenji Shibata

Hiromi Kamogawa

Okikazu Ishiguro

Mitsuharu Kon

Masayuki Yamamoto

Kunikatsu Yoshida

A wet-type flue gas desulfurization method and plant making use of a solid desulfurizing agent in which exhaust gas exhausted from a combustion apparatus such as a boiler is brought into contact with absorbing liquid to absorb sulfur oxide from the exhaust gas into the absorbing liquid followed by neutralization of the absorbing liquid containing the sulfur oxide thus absorbed. The solid desulfurizing agent is selectively retained in an absorbing liquid neutralizing zone and the absorbing liquid, containing water as a main constituent and solid products formed from the absorbed sulfur oxide, is selectively removed from the neutralizing zone. In the neutralizing zone the upward flow of the absorbing liquid, optionally augmented by an upward flow of air or water, forms a fluidized bed of limestone particles, thereby preventing coating of the limestone by gypsum and thereby retaining reactivity of limestone. According to the present invention, coexistence of Al and F in the absorbing liquid seldom deteriorates the desulfurizing performance. Further, it is possible to reduce power and cost required to grind limestone and to achieve a higher desulfurizing performance.

Wet-type flue gas desulfurization plant and method making use of a solid

Wet-type flue gas desulfurization plant

An apparatus for wet process exhaust gas desulfurization including a spraying portion for spreading absorbent slurry including calcium compound, an absorbing tower for bringing the absorbent slurry sprayed from the spraying portion into contact with exhaust gas including sulfur oxides from opposite directions so as to absorb the sulfur oxides in the exhaust gas into the absorbent slurry, a slurry tank disposed below the absorbing tower for receiving the absorbent slurry from the absorbing tower, a plurality of stirrers for stirring each stirrer being an axial flow type agitator having a propeller, and circular system for circulating the absorbent slurry from the slurry tank to the spraying portion. The apparatus further includes a plurality of nozzles for feeding oxidizer gas including oxygen into the absorbent slurry from a backside of each propeller towards a periphery thereof uniformly with respect to a circumferential direction, thereby bubbling the oxidizer gas finely around each propeller.

Wet-type exhaust gas desulfurizing apparatus

Optimum overall operation of a whole plant including a combustion unit such as a boiler and a wet-process flue gas desulfurization unit comprising an absorption column for removing sulfur dioxide from a flue gas from the combustion unit by absorption using a slurry of an absorbing agent such as limestone powder circulated through absorption column, recycle pumps for circulating the slurry through the absorption column and oxidation air blowers for supplying an oxidation air to the absorption column and a recycle tank is controlled by anticipating a future pH value of the circulating slurry and a future inlet sulfur dioxide content of the flue gas from a present pH value of the circulating slurry and a present inlet sulfur dioxide content of the flue gas and their change rates by computing, anticipating a future desulfurization ratio from both the anticipated pH value and inlet SO.sub.2 content and a recycle rate of the slurry, and controlling the recycle rate of the circulating slurry on the basis of the anticipated desulfurization ratio, where a desired desulfurization ratio can be readily and continuously maintained against any change in fuel species and load of a boiler with reduced utility consumption.

Method for controlling wet-process flue gas desulfurization

A flue gas desulfurization process by which gypsum can be recovered; the amount of water used therein is small, the effluent is treated in a closed system, the equipment used is minimized, and no scaling occurs; and an apparatus therefor are provided, the process including the following first process and second process: the first process comprising a cooling step of cooling and dedusting a SO.sub.2 -containing flue gas and removing acidic gases, an absorption step of contacting the cooled gas with a slurry containing limestone and lime to absorb and remove SO.sub.x and form CaSO.sub.3, a pH-adjusting step of adding H.sub.2 SO.sub.4 to the resulting slurry, an oxidation step of blowing an oxygen-containing gas in the pH-adjusted slurry to form gypsum, a step of concentrating the resulting gypsum slurry, a step of adjusting the concentration of the resulting slurry, a step of centrifugally separating gypsum, and a step of treating the effluent discharged from the cooling step, and the second process comprising, in the first process, further feeding the slurry of the absorption step to the cooling step where unreacted limestone is reacted with SO.sub.2 to form CaSO.sub.3 .

Flue gas desulfurization process

A flue gas desulfurization process capable of producing a high purity gypsum and also making equipment employed as minimum as possible is provided, which process comprises the steps of cooling and dedusting flue gas containing SO.sub.x ; contacting the cooled gas with a slurry containing limestone to remove SO.sub.x by absorption and also form CaSO.sub.3 ; controlling the pH of the resulting slurry and then blowing air therein to form gypsum; and separating gypsum from the resulting slurry. As a modification of the above process, the slurry of the above second absorption step is further fed to the above first cooling step where unreacted limestone and SO.sub.x are reacted to form CaSO.sub.3.

Limestone-gypsum flue gas desulfurization process

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Kure, Japan

Shigeru Nozawa